Device for stacking sheet-shaped materials on sheet stacks

ABSTRACT

A device stacks sheet-shaped materials ( 1, 1′ ) on a sheet stack with at least one deflecting element ( 82, 82′ ), mounted above the sheet stack and in the area of the leading edges ( 6, 6′ ) of the stacked sheet-shaped materials ( 1, 1′ ) so that it can rotate, and exhibiting at least one deflecting fin ( 83, 83′ ), whereby deflecting element ( 82, 82′ ) is driven and mounted so that it can rotate, whereby one deflecting fin ( 83, 83′ ) is in contact with the topmost sheet-shaped material ( 1 ) of the sheet stack that has already been stacked so that the leading edge ( 6′ ) of the next sheet-shaped material ( 1 ) to be stacked is deflected until the deflecting element ( 82, 82′ ), after stacking this next sheet-shaped material ( 1′ ), rotates far enough that a deflecting fin ( 83, 83′ ) is in contact with this sheet-shaped material ( 1′ ) that is now lying topmost.

TECHNICAL FIELD

[0001] The present invention relates to a device for stackingsheet-shaped materials on sheet stacks, and more particularly to adevice for stacking sheet-shaped materials on sheet stacks found mainlyin digital printing machines/copiers or in print further processingmachines.

BACKGROUND

[0002] In devices for printing and for processing printed materials, theprint materials are stacked on a sheet stack in a large number of cases.In order to make further processing easier, e.g. binding a sheet stackof printed materials together to form a book or transporting largersheet stacks, it is advantageous if the sheet-shaped materials form asheet stack that is as square-shaped as possible, in which the sideedges of the sheet-shaped materials lie exactly on top of each other.Typically, the sheet stack is aligned in different ways, in particularwith straighteners that move the sheet stack, especially in the area ofthe topmost printed material, at regular intervals with an impact andusually align them against a stop.

[0003] Stacking sheet-shaped materials is understood here as when thesheet-shaped material is moved into a position in which it has norelative speed with respect to the sheet stack in transport direction,i.e., it is essentially at rest, but not yet necessarily aligned so thatthe side edges are even and not necessarily contacting the entiresurface of the sheet-shaped material lying below it in the sheet stack.In the case described here, a sheet-shaped material is alreadyconsidered stacked if its leading edge is not in contact with theleading edge of the sheet-shaped material lying below it, but thesheet-shaped material is no longer being transported and the majority ofit is in contact with the sheet stack.

[0004] Typically, the sheet-shaped materials are processed individuallyand along a transport path in devices for printing and processing printmaterials, whereby the transport path lies essentially in the plane ofthe sheet-shaped materials. In order to form a sheet stack, theindividual sheet-shaped materials are transported on a transport path,frequently laterally toward the sheet stack of sheet-shaped materialsalready stacked.

[0005] Alternatively to the option of ejecting the individualsheet-shaped materials directly over the sheet stack, as is typicallythe case with ejectors of printing machines, frequently the procedure issuch, especially in digital printers or copy machines, that the leadingedge of the new sheet-shaped material to be stacked comes in contactwith the topmost sheet-shaped material in the sheet stack when it isbeing stacked and then is slid up to a stop over the sheet-shapedmaterial lying topmost on the sheet stack. Then the sheet-shapedmaterial can be aligned laterally, if necessary.

[0006] This process that is typical for the working sequence, especiallyof a digital printer or copy machine, involves a problem if it is a caseof sheet-shaped materials that have a hole pattern, such as a 2, 3, 4 or5 hole pattern used for storing sheet-shaped materials in binders orfolders. On the other hand, it can also be a hole pattern that is madein the sheet-shaped material for a wire or plastic comb binding or awire or plastic spiral binding.

[0007] In sheet-shaped materials in which such a hole pattern isprovided, there is a possibility with a lateral placement method, inwhich the following sheet is slid with friction contact over thesheet-shaped material that is already stacked, that the hole pattern ofthe following sheet-shaped material or the comers of the followingsheet-shaped material may catch in the holes of the hole pattern of thesheet-shaped material that is already stacked. It is especially easy forsuch catching to occur if the hole pattern involves a hole pattern for awire or plastic comb binding or a wire or plastic spiral binding, sincea hole pattern provided for this is generally arranged close to the sideedges of the sheet-shaped material.

[0008] In particular, a “donkey ear” that is bent downward on asheet-shaped material that will be stacked on a sheet stack of the sametype of sheet-shaped materials gets caught in a hole of such a row ofholes for wire or plastic comb binding or wire or plastic spiral bindingif the side edges of the following sheet-shaped material aresufficiently misaligned in respect to the side edges of the sheet stack.However, such a misalignment can rarely be prevented completely whenusing paper guides.

[0009] An alignment of the sheet-shaped materials in the sheet stack sothat the side edges are even can no longer be achieved if a corner of asheet-shaped material catches in the hole pattern of a sheet-shapedmaterial lying below it. This leads to the fact that the hole patternsin the individual sheet-shaped materials in the sheet stack are nolonger aligned, which in turn has the consequence that a subsequentbinding of the sheet-shaped materials using wire or plastic comb bindingor using a wire or plastic spiral binding can no longer be carried out.

[0010] Therefore, it is desirable to have a device for stackingsheet-shaped materials that does not have the problems mentioned,especially when stacking sheet-shaped materials that are provided with ahole pattern.

[0011] A device is known from the German Patent DE 38 39 305 forstacking, in a stack, sheet-shaped materials that are suppliedindividually and above the stack. This device has a stop assigned to theleading edge of the sheet-shaped material, in the area of which astapling device and a sheet stack removal device are arranged. Above thesheet stack and placed before the stapling device, when viewed in thesheet intake direction, there is a shaft that can be rotated in bothdirections by a stepper motor that is mounted perpendicular to the sheetinlet device and parallel to the top of the sheet stack. Separatingfingers are mounted on the shaft that when lowered onto the sheet stackform a contact diagonal for subsequently incoming sheets and separatethem from the sheet stack lying below them. If the sheet stack was takenfrom the collecting container, the separating fingers lay the sheetsheld back down in the collecting container by swiveling in the directionof the sheet intake. After stacking the sheets, the separating fingerscontinue rotating in the same direction of rotation until they reach theinitial position lying above the sheet stack. The task of the inventiondescribed in DE 38 39 305 is to design a device of this general type insuch a way that free access is provided for further processing devicesin the mounting area of the retainer device.

[0012] German OLS DE 23 63 224 discloses a spring-action, flap-typestacking element for a device which stacks sheet-shaped materials in acollecting shell, whereby the stacking element is mounted on a drivenshaft and, after each sheet released into the collecting shell, it turnsaround the shaft in such a way that tension is initially built up in thestacking element and then released suddenly during further rotation andin this process the topmost sheet-shaped material lying in thecollecting shell is driven against a stop.

DISCLOSURE OF THE INVENTION

[0013] According to the present invention, a deflecting fin of adeflecting element lies, practically at all times, on the firstsheet-shaped material lying topmost on the sheet stack in the area ofthe leading edge of the sheet-shaped material. In this case, the leadingedge of the sheet-shaped material is understood to mean that outer edgethat goes first in transport direction. The leading edge of a secondsheet-shaped material that is transported laterally to the sheet stackis deflected upward by the deflecting fin. As soon as the secondsheet-shaped material comes to rest, the deflecting element turns aroundits axis so that the deflecting fin is pulled out laterally from underthe second sheet-shaped material and during further rotation adeflecting fin now comes in contact, from above, with the secondsheet-shaped material in the area of the leading edge and remains there.This procedure repeats with each new sheet-shaped material transportedfor stacking. Because of the lateral removal of the deflecting fin underthe leading edge of the sheet-shaped material, the leading edge dropsvertically onto the leading edge of the sheet-shaped material lyingbelow it. A catching of the corners of the upper sheet-shaped materialin the holes of a hole pattern in the lower sheet-shaped material isvirtually ruled out especially by this vertical movement. It is clear tothe person skilled in the art that the number of deflecting elements canvary, this means that one, two, three, four or more deflecting elementscan be used.

[0014] In addition, the material for the deflecting fin is selected insuch a way that the upper side of the deflecting fin, with which theleading edge of a newly delivered sheet-shaped material is deflected,exhibits only little friction so that the newly delivered sheet-shapedmaterial can be easily deflected; on the other hand, the bottom side ofthe deflecting fin exhibits greater friction with the sheet-shapedmaterial lying below it. Because of this, the lateral removal of thedeflecting fin carries the lower sheet-shaped material, as a result ofthe increased friction, forward against the stop and thereby providingadditionally alignment. For example, this functionality can be achievedby a deflecting fin of spring steel with rubber coating on the bottom.

[0015] Also according to the invention, the sheet stack is limited intransport direction by a stop, whereby the stop exhibits a radius in thearea of the upper edge of the stack of the stacked sheet-shapedmaterials opposite the transport direction. This stop is used as alimiter for the movement of the sheet-shaped materials during transportto the sheet stack. Alternatively, the stacking of the sheet-shapedmaterials on the sheet stack on a flat stacking element can be improvedby using several, in particular two, stops.

[0016] Thus, if a sheet-shaped material lies with its leading edge onthe deflecting fin in contact with the stop, most of the surface of thissheet-shaped material lies on a stacking element or the topmostsheet-shaped material of a stack that is forming on the stackingelement. However, this also depends on the thickness, and thus thestiffness, of the sheet-shaped material, a thicker sheet-shaped materialmay not lie entirely flat on the deflecting fin but be deflected overits entire length. If the deflecting fin is now pulled out from underthe next sheet-shaped material by rotation around its axis, the trailingedge of the sheet-shaped material ideally remains unchanged at itsprevious position and the previously deflected leading edge is gentlylowered onto the stack of sheet-shaped materials. In this process, theleading edge follows with about the radius that is provided on the stopin this area. Lateral offset that would otherwise result by deflectionof the leading edge, if this were deflected against a straight stop, ishereby prevented.

[0017] This means the radius stops the deflected sheet-shaped materialbefore reaching the position that it would assume with a straight stop.Because of this, the trailing edge of the sheet-shaped material comes torest on the trailing edge of the sheet-shaped material lying below itand no movement opposite the transport direction is necessary duringlowering of the sheet-shaped material. A movement such as this needs tobe prevented especially when the incoming sheet-shaped material exhibitsa hole pattern along its leading edge. In this process, a hole patternconsisting of a number of square holes, as is used for wire comb orplastic comb binding, is especially critical. These holes frequentlyhave irregular edges that can catch on each other during lateralmovements. If the holes of different sheet-shaped materials catch oneach other, a matching alignment of all holes of the hole pattern in thestack is no longer possible in general. And if the hole patterns of thesheet-shaped materials in the stack do not match, it is usually nolonger possible to implement a planned wire comb or plastic combbinding. Therefore, it is advantageous, particularly in the area of theleading edge, to stack such sheet-shaped materials very carefully andabove all vertically without lateral displacements. This is achievedwith this characteristic feature of the device according to theinvention.

[0018] Also according to the invention, a deflecting element exhibits astructure that is essentially equal in area to that of the radius of thestop. This structure may be a leading edge stop that is provided on oneside element of at least one of the deflecting elements.

[0019] By limiting the transport path by means of a stop, anadvantageous alignment of the sheet-shaped materials is carried out attheir leading edge. This is advantageous if it is a case where at leastsome sheets of the sheet-shaped materials have at least partiallyirregular outer contours, such as with register sheets or sheets withtab indents. In order to stack such sheet-shaped materials havingirregular outer contours with side edges even at least in sections,these sheet-shaped materials have at least one straight side which foralignment can be guided at a stop and/or subsequently aligned withstraighteners, in this case the leading edge of the sheet-shapedmaterial. In most cases, register sheets or sheets with tab indents suchas these have three common edges.

[0020] Also according to the invention, the stop is mounted so that itcan swing downward so that laterally a transport path is released for asheet stack of sheet-shaped materials stacked on the flat stackingelement. This is advantageous if a set of sheet-shaped materials wasstacked into a sheet stack at the stop and now will be removed laterallyas a stack, for example by an operator or by a further processing devicesuch as a binding device for books. Sliding the stop in vertical orlateral direction or moving the stop from the lateral transport path bya non-swinging movement is also contemplated.

[0021] Also according to the invention, the deflecting fins aremanufactured of an elastic material. It is possible to prevent the topsheet-shaped material from slipping due to pulling the deflecting finout with respect to the position of the sheet-shaped materials lyingunder it by selecting a smooth, elastic material as the material for thedeflecting fin, such as a spring steel or various plastics, and byensuring that the movement is carried out with adequately high speed. Inaddition, the danger of damaging the sheet-shaped materials isconsiderably reduced by selecting an elastic, flexible material.

[0022] Also according to the invention, the deflecting elements have, onat least one side near the deflecting fins, side elements whereby thesurface of the side elements is formed at least in sections in such away that during rotation of the deflecting elements the surface of theside elements lowers the leading edge of the topmost sheet-shapedmaterial onto the stack of sheet-shaped materials. A side element may beassigned to each side of each deflecting element. The side elements maybe essentially disk-shaped, although star-shaped side elements are alsoconceivable. The side elements may be on the same axis with thedeflecting fins. The side elements have surfaces that mostly match eachother and thereby are similar to a roller cut into disks. The sideelements may be manufactured of injection molding material and as muchas possible are lightweight. For weight reduction, the side elements mayexhibit concentric holes or a spoke-like structure. The side elementsare provided perpendicular to the transport direction as uniformly andfrequently as possible.

[0023] Also according to the invention, at least one side elementexhibits a tab following the deflecting fin in the rotation direction ofthe deflecting element, the dimensions of the tab prevent thesheet-shaped materials that have already been stacked in the area of theleading edges of the sheet-shaped materials from spreading out. This tabmay be formed on all side elements. The tab ensures the spatialseparation between the stack and an incoming sheet-shaped material inthis area.

[0024] Also according to the invention, the surface of at least two sideelements is formed in such a way that these serve, at least in part, asa vertical stop for the deflected sheet-shaped material. This prevents apossible upward spreading of the leading edges of the incomingsheet-shaped material, whereby stacking reliability is increased. Asalready described above, the side elements may have an additionalarc-shaped leading edge stop that is essentially congruent with theradius of the stop a few 100 μm behind the radius of the stop intransport direction. Both vertical stop and leading edge stop arelocated in their operating position when the deflecting fin contacts thetopmost sheet-shaped material in order to deflect an incomingsheet-shaped material.

[0025] Also according to the invention, the surface of at least one ofthe outer side elements is formed in such a way that in the area of thetip of the deflecting fin, the side element exhibits a recess. In thiscase, outer side elements are understood as the side elements that areat the greatest distance from the centerline of the transport direction.In another alternative embodiment, the side elements are always arrangedin pairs around a deflecting fin, whereby the side elements placedcloser to the centerline of the transport direction exhibit an upperstop for sheet-shaped materials, as was already described above, andwhereby the other side elements in this area already have the recess.The recess is provided to prevent the outside edges from bumping intothe side elements at this position during a lateral alignment of anincoming sheet-shaped material.

[0026] Also according to the invention, an alignment of the sheet-shapedmaterials is carried out by lateral alignment means. To do this, a firststraightener and a second opposite straightener are mounted diagonal tothe transport path in the flat stacking element, whereby the first andsecond straightener work together in order to laterally align the sheetstack that develops after a number of sheet-shaped materials arestacked. This aligning process may be repeated for each individualarriving sheet. The first or second straightener may be provided withelastic bristles that compensate elastic sheet tolerances duringstraightening. An alignment of the sheet-shaped material in the sheetstack with side edges even can be achieved because of the straighteningof the stacked sheet-shaped materials, especially if the sheet-shapedmaterials do not immediately land at the location provided on the flatstacking element.

[0027] Also according to the invention, at least two deflecting elementsare mounted essentially symmetrical to the centerline of the transportmovement. This may be a case of four or six deflecting elements, butalternatively an odd number of deflecting elements can also be providedthat are arranged symmetrically to the centerline of the transportdevice.

[0028] In digital printing machines and copy machines, there are mainlytwo different concepts for guiding and alignment of sheet-shapedmaterials on their path along the transport path through the digitalprinting machine or the copy machine. One concept provides for analignment of the sheet-shaped materials on one side edge that is thesame for all formats of sheet-shaped materials that are processed withsuch a digital printing machine or copy machine. The other conceptprovides for guiding the sheet-shaped materials always centrally alongthe transport path through the digital printing machine or the copymachine, i.e. to provide an alignment with respect to the center line ofthe sheet-shaped material to the center line of the transport path thatis the same for all formats of sheet-shaped materials that are processedwith such a digital printing machine or copy machine. Both concepts haveadvantages and disadvantages. The latter concept is suitable forprocessing operations on the sheet-shaped material that are carried outsymmetrically to the center line of the sheet-shaped material, say theapplication of a symmetrical hole pattern in the sheet-shaped material.Also, the lifting of one leading edge, especially in the area of thecorners of a sheet-shaped material, may then be carried out if thedeflecting elements are arranged symmetrically to the center line of thesheet-shaped material and even if the center line of the sheet-shapedmaterial and the center line of the transport path lie on top of eachother.

[0029] Also according to the invention, the deflecting elements aremounted to slide laterally and are in active connection with a threadedshaft with two opposing threads. By rotation of the threaded shaft, theposition of the deflecting elements is changed transverse to thetransport direction. If two deflecting elements are provided, wherebyeach one of the deflecting elements is assigned to one of the threads ofthe threaded shaft, in this case the distance of the two deflectingelements from each other can be varied since the threads on the threadedshaft are opposing. Depending on the direction of rotation of thethreaded shaft, the two deflecting elements get closer together orfurther apart from each other. If the two threads on the threaded shafthave the same pitch, the position of the deflecting elements changes insuch a way that deflecting elements mounted symmetrically to the centerline of the transport path continue to be arranged symmetrically to thecenter line of the transport path. However, it is within the scope ofthe invention to also provide threads with different pitches, which thencan be used to change the distance between the deflecting elements andalso a lateral displacement of the center point between the deflectingelements. This would be advantageous for alignment of the sheet-shapedmaterials at one side edge instead of to the centerline.

[0030] Also according to the invention, the outermost deflectingelements are mounted so that they can be moved depending on thedimensions of the sheet-shaped materials. The position of the deflectingelements changes depending on the dimensions of the sheet-shapedmaterials. The sheet-shaped materials that are used in a digitalprinting machine/copy machine or print further processing machine, ofwhich the device according to the invention is a part, can havedifferent width and length along the transport path so that differentformats of the sheet-shaped materials may be processed or sheet-shapedmaterials with different orientation, such as portrait format orlandscape format may move along the transport path. Both occurrelatively frequently, especially in digital printing machines/copymachines or print further processing equipment since such devicestypically already contain a large number of paper supplies or devicesfor changing the orientation of the sheet-shaped materials. This meansmany printers/copiers contain paper trays for paper of A3 and A4 as wellas A4R format. It is advantageous if the position of the deflectingelements is adjusted to the respective format of the sheet-shapedmaterials. This can be achieved simply in that a control carries out aformat-dependent adjustment of the position of the deflecting elementsby controlling the rotation of the threaded shaft before receiving asheet-shaped material on the sheet stack. In this process, theadjustment of the position of the deflecting elements can also becarried out in batches, i.e. before each order for the processing ofsheet-shaped materials with the same format. In this process, thecontrol receives the information about the format, and thus the width ofthe sheet-shaped materials, either from the user, a higher-levelcontrol, sensors or other information sources.

[0031] Also according the invention, grooves are provided on the shaftthat holds the deflecting elements, at specified positions by means ofwhich the deflecting elements are mounted with exact position andreproducibly on the shaft. This may be carried out with an appropriateconical pin that is screwed into these grooves. An adaptation to aformat change can also occur in that the pin is loosened, the deflectingelement is slid to another groove provided for this along the shaft andthen fixed with the pin at the new position so that it cannot slip.

[0032] Also according to the invention, the device has a measuring unit,by means of which the position of the outermost deflecting elements canbe determined. This is in particular an optical sensor that specifiesthe zero position of the outermost deflecting elements. If there is achange in position of the outer deflecting elements, first the zeroposition is approached and after that the required position isapproached. This may be necessary for a format change of thesheet-shaped materials to be stacked. Because of this, the process canbe automated. This means, for example, a higher-level control candetermine the format of the sheet-shaped materials to be stacked andautomatically initiate the format change. By approaching the zeroposition, the positioning is calibrated each time. For instance, a lugcan be provided as a sensing element on one of the deflecting elements,which runs through the optical sensor.

[0033] Also according to the invention, the device is used for stackingsheet-shaped materials that exhibit a hole pattern that is essentiallyparallel to the leading edge. In this case, the deflecting fin isarranged in the device according to the invention in the area of theoutermost holes of the hole pattern so that the deflecting finsessentially cover these outermost holes of the hole pattern. Because theoutermost holes of the hole pattern are covered, the risk previouslydescribed of “donkey ears” of a subsequent sheet-shaped materialcatching in the holes of the print material lying below it is prevented.The probability that a corner of a sheet-shaped material can catch in ahole of the hole pattern of the print material lying below it depends onthe lateral imprecision of the stack of sheet-shaped materials on thesheet stack. Since devices of this type generally are fairly precise,the problem is only notable in principle for the outermost hole of ahole pattern. Therefore, it is adequate to cover each of the outermostholes of a hole pattern to basically rule out catching of corners andholes. In this process, the deflecting elements are arranged in apreferred embodiment in such a way that when the sheet-shaped materialsare stacked, the hole pattern lies behind the tip of the deflecting finin transport direction, when the tip just touches the topmostsheet-shaped material in the stack. This prevents a lateral incomingsheet-shaped material from getting into the hole pattern of the topmostsheet-shaped material placed on the stack, since this is deflectedupward by the deflecting elements before this happens.

[0034] The tip of the deflecting fin has a curve-shaped form, such as asemi-circle or at least an arc section, parabola-shaped curve or thelike. This geometry further improves the deflecting behavior of thedeflecting fins, since it prevents an incoming sheet-shaped materialfrom bumping against a straight edge of the deflecting fin. Thedeflecting fin may have a symmetrical narrowing of the stop in thedirection of the deflecting fin tip. An incoming sheet-shaped materialthat has run up to the deflecting fin, contacts the stop and now isbeing laterally aligned and exhibits a hole pattern of square holes inthis area, will not catch, when moving laterally, on the deflecting finswith the edges of the square holes running parallel to the transportdirection because of this symmetrical narrowing. The edges of a squarehole can be slid smoothly onto the deflecting fin so that there is notilting and the lateral alignment process can occur without problems.

[0035] Also according to the invention, a chamfer is embossed on the tipof the deflecting fin so that the tip of the deflecting fin offers astill smaller step for an incoming sheet-shaped material and there willbe no tilting of leading edge of the sheet-shaped material. Damage tothe leading edge of the incoming sheet-shaped material is reducedbecause of this.

[0036] Also according to the invention, at least one elastic driving finis mounted so that it can rotate above the stack of sheet-shapedmaterials in such a way that during rotation of the driving fin, the endof the driving fin comes in contact with the topmost sheet-shapedmaterial on the stack and moves this topmost sheet-shaped material intransport direction. These types of driving fins are used for improvedalignment of the sheet-shaped materials at a stop. The invention mayhave at least two driving fins, whereby at least one driving fin is moreelastic and longer than at least one other driving fin. Two pairs ofdriving fins may be mounted alternately by 90° around a shaft. Thedriving fins consist in particular of silicone in order to achieve thedesired elasticity and the necessary adhesion for driving the incomingsheet-shaped materials forward. Generally in this arrangement, only thelong and more flexible driving fins come in contact with the incomingsheet-shaped materials. The short driving fins may be cut off in such away that they only come in contact with sheet-shaped materials that maybe distorted in the collecting area due to their stiffness and can notbe optimally further transported by the longer driving fins to their endposition above the stack of sheet-shaped materials.

[0037] Also according to the invention, at least one hold-down element,which can tip around a hold-down shaft and guide the next sheet-shapedmaterial onto the stack of sheet-shaped materials, is mounted above thestack of sheet-shaped materials. There may be a plurality of hold-downelements that are distributed symmetrically to the centerline of thetransport direction over the width of the sheet-shaped materials. Thehold-down elements may exhibit counterweights that optimize the contactforce on the sheet-shaped materials so that as little additional forceas possible is necessary to overcome any friction forces that may occurbetween the hold-down elements and the incoming sheet-shaped material.Still enough force is applied to actually hold down the incomingsheet-shaped materials.

[0038] Also according to the invention, at least one hold-down elementexhibits a hold-down lug that extends into a measuring unit, whereby thesignal of the measuring unit is used to determine the height of thestack of sheet-shaped materials. The information on the stack height canbe used in many ways, such as to check that all of the sheet-shapedmaterials of an order have arrive or in order to give a warning if thestack has reached its maximum height and must be taken out. Alternativemeasuring methods, such as capacitive or magnetic or other measuringmethods that use electromagnetic waves or ultrasound of all differentwavelengths, are considered as equivalent here.

[0039] Also according to the invention, the device exhibits aheight-adjustable stacking element, on which the stack of sheet-shapedmaterials is formed, and a control, whereby the control uses the signalof the measuring unit in order to keep the position of the topmostsheet-shaped material essentially constant using the height-adjustablestacking element. Because of this, the height-adjustable stackingelement and thus the stack will be lowered by the thickness of theincoming sheet-shaped material in accordance with the signal of themeasuring unit after each incoming sheet. Because of this, the stop,which is provided with a radius, always remains optimally aligned to theincoming sheet-shaped materials. The same is true for the position ofdriving fins, that drive an incoming sheet-shaped material against sucha stop, or even for the deflecting fins themselves and the deflectingelements. The height-adjustable stacking element can also be used tolower the stack of sheet-shaped materials below a fixed stop such thatthe stack can be removed in transport direction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1 a schematic side view of a first embodiment of the deviceaccording to the invention;

[0041]FIG. 2 a schematic top view of a first embodiment of the deviceaccording to the invention;

[0042]FIG. 3 a schematic side view of a second embodiment of the deviceaccording to the invention;

[0043]FIG. 4 a schematic top view of a second embodiment of the deviceaccording to the invention;

[0044]FIG. 5 a schematic partial side view of a third embodiment of thedevice according to the invention;

[0045]FIG. 6 a schematic partial top view of a third embodiment of thedevice according to the invention;

[0046]FIG. 7 a schematic, isometric partial view of the third embodimentof the device according to the invention;

[0047]FIG. 8 a schematic isometric enlargement of a detail of a thirdembodiment of the device according to the invention;

DETAILED DESCRIPTION

[0048] Referring now to the drawings wherein like reference numeralsdesignate like or corresponding parts throughout different views, thereis shown in FIGS. 1 to 8 a schematic side view and/or schematic top viewof three embodiments of the device 100, 100′ according to the invention,whereby the components of the device marked with apostrophes indicate analternate embodiment. Apart from this, the same reference charactersdesignate the same elements in all figures. Drive and/or guide means andcams know to the person skilled in the art for operating the device areshown only schematically and/or are described in only a general way.Stepper motors are especially suitable as drives since their movementcan be controlled precisely and in a simple way using control meansknown to the person skilled in the art.

[0049] The device 100, 100′ according to the invention is part of asheet-processing printing, copying or further processing device known tothe person skilled in the art, especially part of a sheet-processingprinting or further processing device such as is used to storesheet-shaped material.

[0050] As can be seen in FIG. 1, a sheet-shaped material 1 that will bestacked with edges even, is located on a transport path 2 marked withreference character 2, passing through a sheet-processing printing orprint further processing device that is not shown. Along the transportpath 2, the sheet-shaped material has a length that is identified withreference character 1′ in FIG. 1. The sheet-shaped material 1 typicallyconsists of paper with different sheet weight, or plastic films, ortransparencies, or it can also be a mixture of papers and transparenciesor a mixture of papers with different weights per surface area, such asfor the cover of a book in contrast to the pages of the book body,however, the outer edges of the sheet-shaped material that are collectedin a sheet stack should essentially have the same dimensions. Whensheet-shaped materials 1 are stacked with edges even in a followingsheet stack, such as after the stacking of all the pages of a book to bebound, all the individual sheet-shaped materials 1 have essentially thesame dimensions again. In any case, these essentially equal dimensionsof the sheet-shaped materials 1 do not necessarily correspond to theessentially same dimensions of the sheet-shaped materials 1 of thepreceding sheet stack since it can involve a new sheet format or a newpage orientation.

[0051] The sheet-shaped materials 1 are guided and transported on thetransport path 2, first by a first transport roller 12, which is mountedabove transport path 2, and a second transport roller 22, which ismounted below transport path 2. Transport path 2 has a center line M1that coincides with the centerline of the sheet-shaped materials 1 (seeFIG. 2 or FIG. 4), irrespective of the format or alignment ofsheet-shaped materials 1. With transport such as this, we speak of acenterline registration of the sheet-shaped materials 1. However, thedevice 100, 100′ according to the invention is not restricted to thetransport of sheet-shaped materials 1 with center line registration,sheet-shaped materials 1 that are registered along their side edges canalso be stacked with side edges even using the device 100, 100′according to the invention. Instead of the transport rollers 12, 22,other transport elements that are not shown, but are known to the personskilled in the art, can be used, such as conveying bands or belts.

[0052] Below and in front of the two transport rollers 12, 22, a flatstacking element 50 is mounted. The flat stacking element 50 exhibits alength along transport path 2 that corresponds at least to length 1″ ofthe largest sheet-shaped material 1 that is to be stacked. The flatstacking element 50 has guiding and bearing elements that are not shownbut are known to the person skilled in the art, and drive and controlsystems which make a controlled, essentially vertical movement of theflat stacking element 50 possible. To facilitate the lateral removal ofa sheet stack of sheet-shaped materials 1 from the flat stacking element50, the flat stacking element 50 exhibits an angled slope 50′downstream.

[0053] Controller 70 controls the vertical position and the verticalmovement of the flat stacking element 50, so that during the stacking ofsheet-shaped materials 1, the upper edge of the sheet stack essentiallyhas a constant height. To do this, the flat stacking element 50 drops,according to the thickness of the sheet-shaped materials 1 stacked,after each new sheet-shaped material 1 is stacked. Alternatively,controller 70 can also allow that the flat stacking element 50 will onlybe lowered after every nth sheet-shaped material. Controller 70 cancontain an instruction, stored in a control logic that specifies a ratiobetween the sheet thickness and the number of sheet-shaped materials 1to be stacked, after the stacking of which the flat stacking elementwill be lowered. Controller 70 receives information about the thicknessof the sheet-shaped materials 1 from a user, a higher-level control,sensors or other information sources. In addition, controller 70controls a longer, essentially vertical movement of the flat stackingelement 50 in order to ensure a fast removal of the sheet stack.

[0054] The flat stacking element 50 is limited along transport path 2 bya stop 30 that can swing around a pivot point 31. As FIG. 2 shows, thestop is provided in duplicate in an arrangement symmetrical tocenterline MI of the transport path. This arrangement is advantageous,but not imperative for the device 100, 100′ according to the invention,it is within the scope of the capabilities of the person skilled in theart to install this stop in a different number and/or arrangement. Stop30 is mounted so that it can be swung around pivot point 30 in order toensure a lateral removal of the sheet stack of sheet-shaped materials.Alternatively, an essentially vertical or horizontal movement is alsoconceivable within the scope of the invention in order to move the stopout of the way.

[0055] Above the flat stacking element 50, downstream of the twotransport rollers 12, 22, a flexible driving fin 61 that can be drivenin rotation is mounted on a shaft 60. In the embodiment, the driving fin61 is fastened on shaft 60 such that it extends with uniform width onboth sides of shaft 60. Alternatively, a larger number of individualdriving fins 61 can also be provided, especially in order to create adifferent angular distribution on shaft 60. Alternatively, severalsimilarly designed driving fins 61 are mounted along shaft 60symmetrical to the center line MI of transport path 2. Also, the drivingfin 61 can also be designed so that it is bent in a curved line. In thiscase, the direction of the curved line is opposite the rotationdirection, marked with reference character 62, of driving fin 61 aroundshaft 60.

[0056] The driving fin 61 is arranged at a vertical distance from theupper edge of the sheet stack of sheet-shaped materials 1 so that duringrotation around shaft 60 in the movement direction, marked withreference character 62, it comes in contact with the topmostsheet-shaped material 1 and during further rotation transports itfurther due to friction between the driving fin 61 and the sheet-shapedmaterial 1 lying topmost on the sheet stack in transport direction.Driving fin material may be rubber-like or plastic-like material, or acoating on a comparable type of flexible material, such as a springsteel.

[0057] As soon as a sheet-shaped material 1 is slid by the first andsecond transport rollers 12, 22 far enough over the stacking elementthat it is located in the catchment area of driving fin 61, it is guidedin a defined manner due to the friction contact with driving fin 61 anddriven against stop 30. Driving fin 61 drops during further rotationaround shaft 60 and the opposite fin of the driving fin can handle thenext sheet-shaped material 1.

[0058] As soon as the trailing edge of the sheet-shaped material 1leaves the area of contact with the first transport roller 12 and thesecond transport roller 22, the leading edge 6, 6′ of the sheet-shapedmaterial 1 moves, essentially unguided, to the flat stacking element 50up to the point where driving fin 61 comes in contact with the topmostsheet-shaped material 1. Shortly before the trailing edge of thesheet-shaped material 1 leaves the area of contact with the firsttransport roller 12 and the second transport roller 22, the driving fin61 is still not in contact with the sheet stack of sheet-shaped material1, rather there is only a narrow gap between the end of the driving fin61 and the topmost sheet-shaped material 1 that has already been stackedin alignment so that an arriving sheet-shaped material 1 can moveforward under driving fin 61 far enough that driving fin 61 grasps itduring rotation around shaft 60.

[0059] In the area of the leading edge 6, 6′ of sheet-shaped materials1, 1′ on the sheet stack, two deflecting elements 82, 82′ are mounted.In a first embodiment (reference characters without apostrophe used forthe components), the deflecting elements 82 exhibit a bent deflectingfin 83, which with its free end rests with light contact pressure on thestacking element 50 or on a sheet-shaped material 1, 1′ already stackedon the stacking element 50. The deflecting fin 83 is curved in such away that the concave part is open toward the sheet-shaped materials 1,1′ that have been delivered. This results in a deflection diagonal thatpoints somewhat upward between the deflecting fin 83 and its base.

[0060] In the following, a first sheet-shaped material 1, which liesuppermost on the sheet stack, is indicated with a reference characterwithout apostrophe, while on the other hand, a sheet-shaped material 1′to be stacked on top of it is designated with a reference character withapostrophe. The same is true for hole patterns 3, 3′, the outermostholes 4, 4′ of hole patterns 3, 3′, the corners 5, 5′ of thesheet-shaped materials 1, 1′ and for the leading edges 6, 6′ of thesheet-shaped materials 1, 1′.

[0061] The leading edge 6 of the first sheet-shaped material 1 glides onthe stacking element 50 up to stop 30, in front of which thesheet-shaped material 1 comes to rest. Shortly before reaching stop 30,the leading edge 60 is guided onto the deflecting diagonal of thedeflecting fin 83 and thereby slightly raised. After that, deflectingelement 82 rotates 360°. As a result of this movement, deflecting fin 83is pulled away laterally under the leading edge 6 of sheet-shapedmaterial 1 so that the leading edge 6 of sheet-shaped material 1 islowered vertically in front of stop 30. Then deflecting fin 83 is turnedfar enough so that it makes contact, coming from above, withsheet-shaped material 1 and possibly presses it completely on stackingelement 50 if it has not already been completely lowered.

[0062] As FIG. 2 shows, lateral straighteners 41 are mounted on eachside of the flat stacking element 50. Said straighteners 41 are broughtin contact with the sheet stack by means of a movement in the directionof the arrow marked with reference character 42 and in doing sostraighten the sheet stack laterally. In a preferred embodiment, thefirst or the second lateral straightener 41 is provided with elasticbristles (not shown) that compensate for elastic sheet tolerances duringstraightening. In this process, the bristles may be aligned at an angleof 45° to the plane of the flat stacking element 50, but other anglesare also conceivable. Likewise, in an alternative embodiment, one of thelateral straighteners 41 can exhibit a foam-like or other compressiblesurface. The other lateral straightener 41 is designed with a smooth,non-compressible surface.

[0063] First and second straighteners 41 are moved synchronously towardand away from the sheet stack by a controller 70 so that an optimumlateral alignment of the sheet-shaped materials 1 in the sheet stack isachieved. The synchronous movement of the lateral straighteners 41occurs in cycles after each individual sheet-shaped material is stacked.The movement is triggered precisely after the driving fin 61 has pushedthe newly stacked sheet-shaped material 1 against stop 30 and theleading edge 6 of the sheet-shaped material is located on the free endof the deflecting fin 83.

[0064] The next sheet-shaped material 1′ is pushed in the same manner asthe preceding sheet-shaped material 1 by the driving fin 61 against stop30 and in turn the leading edge 6′ of the second sheet-shaped material1′ is lifted by the deflecting fin 83 prior to reaching stop 30. Becauseof the lifting of leading edge 6′, it is possible to prevent, even witha misalignment of corners 5′ of the leading edge 6′ of the secondsheet-shaped material 1 as is shown in FIG. 2, corner 5′ from gettingcaught in hole pattern 3, and in particular, in the outermost hole 4 ofhole pattern 3 of the first sheet-shaped material 1.

[0065] After the lateral alignment of the second sheet-shaped material1′, the deflecting element 82 rotates 360° around its axis again,whereby deflecting fin 83 is pulled out laterally from under the leadingedge 6′ of the second sheet-shaped material 1′ so that the leading edge6′ of sheet-shaped material 1′ lowers vertically in front of stop 30,onto first sheet-shaped material 1 with its side edge even. Thendeflecting fin 83 is rotated far enough that it now comes in contact,from above, with sheet-shaped material 1′ and presses this downcompletely on the first sheet-shaped material 1 if necessary, if thesecond sheet-shaped material 1′ has not already dropped completely.

[0066] During rotation of the deflecting element 82, the firstsheet-shaped material 1 can be pushed again, depending on the surfacefinish of deflecting fin 83, against the stop simultaneously, especiallyif the underside of deflecting fin 83, which faces first sheet-shapedmaterial 1, has a higher friction, as was already described above.

[0067]FIG. 3 and FIG. 4 show a second embodiment of the device 100′according to the invention. It differs in that, instead of a single bentdeflecting fin 83, the deflecting element 82′ exhibits two straightdeflecting fins 83′ and deflecting element 82′ is arranged essentiallybehind stop 30 in transport direction. The free end of one of thedeflecting fins 83′ in turn lies in the area of the leading edges 6, 6′of sheet-shaped materials 1, 1′. In addition, the deflecting fins 83′are positioned at a slight angle with regard to the plane of stackingelement 50 so that a slight deflecting diagonal occurs here that candeflect, upward, the leading edge 6, 6′ of a sheet-shaped material 1, 1′that comes in laterally.

[0068] The procedure of deflecting the arriving sheet-shaped materials1, 1′ and the rotating of deflecting element 82, 82′ repeats for eachsheet-shaped material 1 to be stacked in both embodiments of the device100, 100′ according to the invention. Once the last sheet-shapedmaterial 1, 1′ lies on the sheet stack, the lateral straighteners 41 arebrought into position in contact with the sheet stack, for the loweringof the flat stacking element, so that together with stop 30, amulti-sided guiding of the sheet stack is ensured during the fastlowering. The lateral straighteners 41 are also moved in this process.

[0069] In the embodiment shown of the device 100′ according to theinvention, the deflecting fins are designed so that they are relativelywide and are placed so that they completely cover at least the outermosthole 4, 4′ of hole pattern 3, 3′ in the sheet-shaped material 1, 1′ andthus additionally prevent a catching of comers 5, 5′ and the outer holes4, 4′ of the different sheet-shaped materials 1, 1′. Other combinationsof width, curve form and number of deflecting fins 83, 83′ on thedeflecting elements 82, 82′ may be utilized.

[0070] Both embodiments of the device 100, 100′ according to theinvention have in common the fact that the deflecting elements, as shownin FIG. 1 and FIG. 3, are actively connected to a threaded shaft 80, 80′by way of a coupling 85, 85′. This threaded shaft 80, 80′ exhibits twoopposing threads 81, 81′, on which nuts, run that are secured againstturning and have a non-slip connection with the bearings of deflectingelements 82, 82′, in each case. By rotation of threaded shaft 80, 80′,the deflecting elements 82, 82′ are slid symmetrically to the centerlineof transport path 2, inward or outward, depending on the direction ofrotation of threaded shaft 80, 80′. In particular, the position ofdeflecting elements 82, 82′ changes relative to the centerline oftransport path 2, automatically to the optimum position for the form ofthe sheet-shaped materials to be stacked.

[0071] This optimum position is derived from the width of the deflectingfin 83, 83′, from the distance of the outermost holes 4, 4′ from thecorners 5, 5′ of sheet-shaped materials 1, 1′, from the width of thesheet-shaped materials 1, 1′, etc.

[0072] The automatic sliding of deflecting elements 82, 82′ allows thecontroller 70 to control the drive of the rotation of threaded shaft 80,80′ according to different specifications. The specifications may beinstructions that controller 70 receives from a user, a higher-levelcontrol or sensors with regard to the format of the sheet-shapedmaterials 1, 1′ to be stacked.

[0073] FIGS. 5 to 8 show further details of an embodiment of the deviceaccording to the invention, namely in particular the hold-down elements90, the driving fins 61, and an embodiment of the side elements 82 a, 82b of deflecting elements 82 and a special embodiment of deflecting fins83.

[0074] In this embodiment, stop 30 is fixed, while the stacking element50 is mounted so that it can move vertically, as is indicated by thearrow 52 in FIG. 5. In the area of the upper edge of the stack ofsheet-shaped materials 1 collected on the stacking element 50 and, aboveall in the area of the deflecting fins, stop 30 exhibits a radius 32that represents a leading edge stop mounted out front for the incomingsheet-shaped material 1′.

[0075] In this embodiment, six deflecting elements 82 are mounted on ahexagonal shaft 89, essentially symmetrical to centerline M1 oftransport direction 2. The outer deflecting elements 82 are connected tothreaded shaft 80 by way of couplings 85 and their positions can bechanged on both sides at the same time. In this embodiment, the slidingof the outer deflecting elements 82 is also carried symmetrically tocenterline M1 of transport direction 2. At least one of the outerdeflecting elements 82 has a lug 105 that can extend into a measuringunit 110. The measuring unit in this embodiment is an optical sensor110, in particular a photoelectric barrier 110 that determines the zeroposition of the outer deflecting elements 82. If a change is made to thepositions of the outer deflecting elements 82, the outer deflectingelements 82 first are moved to the zero position in order to then bemoved to the desired position. The desired position can be reached usingthe control of the steps of a stepper motor that is not shown, whichdrives threaded shaft 80. In this way, the exact position of the outerdeflecting elements 82 is ensured. In the embodiment shown in FIGS. 5 to8, both outer deflecting elements 82 have a lug 105, however only one ofthe lugs 105 has a function.

[0076] In the embodiment shown in FIGS. 5 to 8, the deflecting elements82 consist of a deflecting fin 83 and side elements 82 a, 82 b. In FIG.8, one side element 82 a is not shown so that the shape of deflectingfin 83 can be shown better. The deflecting fins 83 are bent spring steelplates that are fastened on one side to the hexagonal shaft. In theircenters, deflecting fins 83 have slots 83 b. A pin (not shown), withwhich the inner, immobile deflecting elements 82 are fastened to thehexagonal shaft 89 so that they cannot slip, runs through this slot.These pins that are not shown are centered at grooves 89′ in hexagonalshaft 89 shown in FIG. 8. These grooves 89′ are provided at differentlocations of the hexagonal shaft 89, which in part correspond todifferent formats of sheet-shaped materials 1, say US or DIN format. Achange between these formats is thus also possible, but requiresoperator intervention.

[0077] The geometry of deflecting fins 83 exhibits a narrowing towardthe free end 83 a, and ends in an arc-shaped tip 83 a. An incomingsheet-shaped material 1′, which has run onto deflecting fin 83, touchesstop 30 and is now aligned laterally and has a hole pattern 3 of squareholes in this area, will not catch with the edges of the square holes onthe deflecting fins 83 during a lateral movement, due to thissymmetrical narrowing of deflecting fin 83. The edges of a square holecan be slid laterally much more smoothly on deflecting fin 83 so thatthere will be no catching and the lateral aligning procedure can becarried out without problems.

[0078] A chamfer is embossed on the tip 83 a of deflecting fin 83 sothat tip 83 a of deflecting fin 83 offers a still lower level forincoming sheet-shaped material 1 and there will be no catching with theleading edge of the incoming sheet-shaped material 1. This reducesdamage to the leading edge of an incoming sheet-shaped material 1. Theembossing may be about a few 100 μm wide and runs parallel to thehexagonal shaft 89.

[0079] Side elements 82 a, 82 b are present in two different versions inthe embodiment shown. What both embodiments of side elements 82 a, 82 bhave in common is that they are essentially disk-shaped. Side elements82 a, 82 b have a surface 86, the majority of which is aligned andthereby is similar overall to a roller cut into disks. Side elements 82a, 82 b may be made of injection-molded material and are as lightweightas possible. For weight reduction, side elements 82 a, 82 b may exhibitconcentric holes.

[0080] All side elements 82 a, 82 b have a tab 87 (cf. FIG. 5) followingthe deflecting fin 83 in rotation direction of the deflecting element82, the dimensions of which prevent a spreading of the sheet-shapedmaterials 1 already stacked in the area of the leading edges ofsheet-shaped materials 1. Because of this tab 87, the spatial separationbetween the stack and an incoming sheet-shaped material 1′ is ensured inthis area. Side elements 82 a, 82 b differ in the area in which thedeflecting fins 83 are mounted in the basic position of deflectingelements 82 above tip 83 a of deflecting fins 83. In this area, sideelements 82 a have a vertical stop 86′ that guides the incomingsheet-shaped materials 1′ against stop 31 and prevents an upwardspreading of the leading edges. This means that sheet-shaped materials 1that have a certain “curl” can also be guided precisely to stop 30. Sideelements 82 b, on the other hand, exhibit a recess 86″ in this area. Therecess 86″ is provided to prevent the outside edges of a sheet-shapedmaterial 1 from colliding with side elements 82 b during lateralalignment. In the embodiment shown, side elements 82 a are provided onboth sides for the two innermost deflecting elements 82 lying closest tothe center line M1 of transport path 2. On the four deflecting elements82 mounted further toward the outside, the side elements 82 a areprovided with the vertical stop surface 86′ on the side of deflectingfins 83 turned toward center line M1 of transport path 2 and on the sideof the deflecting fins 83 turned away from the center line M1 of thetransport path 2 are side elements 82 b with recess 86″. With thisarrangement, a recess 86″ remains at the critical locations andsimultaneously over the entire width of sheet-shaped material 1, thereis a vertical stop 86′ that improves the alignment of the incomingsheet-shaped materials 1′.

[0081] Side elements 82 a that have vertical stop 86′ also have aleading edge stop 88, which is shaped as a circular section and isessentially congruent with the radius 32 of stop 30, and mounted a few100 μm behind radius 32 of stop 30 in transport direction. This leadingedge stop 88 carries out a first rough alignment of the incomingsheet-shaped materials 1′. Both vertical stop 86′ and leading edge stop88 are located in their functional position when the deflecting fin 83lies on the topmost sheet-shaped material 1 of the stack in order todeflect an incoming sheet-shaped material 1.

[0082] In the embodiments shown in FIGS. 5-8, the driving fins 61, 61 a,61 b are designed in different lengths. In this case, there are twopairs of driving fins 61 a, 61 b that are mounted on shaft 60,alternately by 90°. The material of the driving fins 61 a, 61 b issilicon in order to achieve the desired elasticity and the necessaryadhesion for driving the incoming sheet-shaped materials forward. Withnormal papers, only the long and more flexible driving fins 61 b come incontact with the incoming sheet-shaped material 1′. The short drivingfins 61 a with greater bending stiffness are cut off in such a way thatthey only come in contact with sheet-shaped material 1 that becomedistorted in the collecting area due to their stiffness and can notalways be optimally driven against stop 30, 32 by the longer drivingfins 61 b above the stack of sheet-shaped materials 1.

[0083] Above the stack of sheet-shaped materials, hold-down elements 90are mounted so that they can tip around a hold-down shaft 91 and guidethe incoming sheet-shaped material 1′ onto the stack of sheet-shapedmaterials 1. The hold-down elements 90 are distributed, symmetrical tocenterline M1 of transport direction 2, over the width of thesheet-shaped materials 1. At the free end, the outer hold-down elementsare provided with counterweights 92 in order to optimize the contactforce on the sheet-shaped materials 1 so that as little additional forceas possible is necessary to overcome any friction forces that occurbetween hold-down elements 90 and the incoming sheet-shaped material 1′.

[0084] The center hold-down element 90 exhibits a hold-down lug 93 (FIG.5), which extends into a measuring unit 94. The measuring unit 94 is anoptical sensor, especially a photoelectric barrier 94. The signal fromphotoelectric barrier 94 is used to determine the stack height of thesheet-shaped materials 1. The photoelectric barrier 94 is connected tocontroller 70, which controls the height-adjustable stacking element 50with a control circuit in order to keep the position of each topmostsheet-shaped material 1 essentially constant. Because of this, theheight-adjustable stacking element, and thus the stack is lowered by thethickness of the incoming sheet-shaped material 1′ according to thesignal of photoelectric barrier 94 after each incoming sheet-shapedmaterial 1′. Stop 30 is provided with a radius 32, always remainsaligned optimally to the incoming sheet-shaped materials 1′. The same istrue of the position of driving fins 61, 61 a, 61 b that drive anincoming sheet-shaped material 1′ against such a stop 30, 32 or also forthe deflecting fin 83 and deflecting elements 82.

[0085] The outer hold-down elements 90 are mounted so that they arealigned with driving fins 61, 61 a, 61 b in transport direction 2 and inthe area of driving fins 61, 61 a, 61 b exhibit hold-down tabs 95 onboth sides of driving fins 61, 61 a, 61 b (see FIG. 6 and FIG. 7). Theends of the hold-down elements 90 are rounded to reduce the frictionbetween hold-down elements 90 and incoming sheet-shaped materials 1′ andto prevent damage from occurring to the incoming sheet-shaped materials1′. The contact points of hold-down elements 90 lie on a commonimaginary line.

[0086] A movable trailing edge straightener 99 is provided below thesecond transport roller 22, see FIG. 5.

[0087] Although the invention has been shown and described withexemplary embodiments thereof, it should be understood by those skilledin the art that the foregoing and various other changes, additions andomissions may be made therein and thereto without departing from thespirit and scope of the invention.

1. A device for stacking sheet-shaped materials on a sheet stackcomprising: at least one deflecting element rotatably mounted above thesheet stack and in the area of the leading edges of the stackedsheet-shaped materials and having at least one deflecting fin; and, acontroller for driving the deflecting element to rotate in a manner suchthat when one deflecting fin is in contact with a topmost sheet-shapedmaterial of the sheet stack that has already been stacked, the leadingedge of the next sheet-shaped material to be stacked is deflected untilthe deflecting element rotates far enough after stacking the nextsheet-shaped material so that a deflecting fin is in contact with thesheet-shaped material lying topmost.
 2. A device according to claim 1,wherein the sheet stack is limited in transport direction by a stop,whereby the stop exhibits a radius in the area of the upper edge of thestack of the sheet-shaped materials stacked opposite the transportdirection.
 3. A device according to claim 2, wherein the at least onedeflecting element is congruent with the radius of the stop.
 4. A deviceaccording claims 1, wherein at least one deflecting fin has a sideelement and wherein the surface of the side elements is formed at leastin sections in such a way that during rotation of the deflectingelements the surface of the side elements lowers the leading edge of thetopmost sheet-shaped material onto the stack of sheet-shaped materials.5. A device according to claim 4, wherein at least one side elementexhibits a tab following the deflecting fin in rotation direction of thedeflecting element, whereby the dimensions of said tab suppress aspreading of the sheet-shaped materials already stacked in the area ofthe leading edges of sheet-shaped materials.
 6. A device according toclaim 4, wherein the surface of at least two side elements is formed insuch a way that it provides a vertical stop for the deflectedsheet-shaped material.
 7. A device according to claim 4, wherein thesurface of at least one of the outer side elements is formed in such away that it exhibits a recess in the area of the tip of the deflectingfins.
 8. A device according to claim 1, wherein at least two deflectingelements are arranged essentially symmetrical to the center line of thetransport movement.
 9. A device according to claim 8, wherein theoutermost deflecting elements are mounted in active connection with athreaded shaft exhibiting two opposing threads so that they can slidelaterally.
 10. A device according to one of claim 8, wherein theoutermost deflecting elements are mounted so that they can slidedependent on the dimensions of the sheet-shaped materials.
 11. A deviceaccording to claim 10, further comprising a measuring unit for measuringthe position of the outermost deflecting elements.
 12. A deviceaccording to one of claim 1, wherein the tip of the deflecting fins iscurve shaped.
 13. A device according to one of claim 1, furthercomprising at least one driving fin mounted so that it can rotate abovethe stack of sheet-shaped materials in such a way that during rotationof the driving fin, the end of the driving fin comes in contact with thetopmost sheet-shaped material on the stack and moves this topmostsheet-shaped material in the transport direction.
 14. A device accordingto claim 13, wherein at least two driving fins are provided, whereby atleast one driving fin is more elastic and longer than at least one otherdriving fin.
 15. A device according to one of claims 1, furthercomprising at least one hold-down element disposed above the stack ofsheet-shaped materials to guide the next sheet-shaped material onto thestack of sheet-shaped materials.
 16. A device according to claim 15,further comprising a measuring unit and wherein the hold-down elementfurther comprises a hold-down lug that extends into the measuring unit,whereby the measuring unit determines the height of the stack of thesheet-shaped materials.
 17. A device according to claim 16, furthercomprising a height-adjustable stacking element on which the stack ofsheet-shaped materials is deposited and a controller which uses thesignal from the measuring unit to maintain the position of the topmostsheet-shaped material essentially constant using the height-adjustablestacking element.